I. Field of the Invention
The present invention is directed to road building equipment and more particularly to equipment to be used in the construction of snow roads and airplane runways.
II. Description of the Prior Art
The exploration and development of the resources of the polar and subpolar areas of the planet are intended to enhance the quality of mankind's existence. Not surprisingly, problems have arisen on account of this activity. One such problem is the difficulty of travel between isolated locations separated by terrain covered with ice and snow. While specialized transport devices are known, their design and manufacture result in a not inconsiderable cost. Part of this cost is the lack of utility of these transport devices in areas which are not covered by ice and snow. The snowmobile is typical of such devices.
Roads constructed from frozen snow or ice, generically referred to as "snow roads", have been offered as a solution. A snow road generally consists of a layer of snow over which water has been applied, which is then compacted and allowed to freeze. The term will be used throughout this application to refer not only to roads but to airplane runways as well. This results ideally in a hard and stable surface suitable for conventional vehicular travel. The problems of clearing deep ice and snow from conventional road or runways, and of the need and expense for specialized vehicle design and construction, are thereby avoided in part.
While several devices and methods for making snow roads are known, they generally have the drawbacks of complicated construction or inefficient operation. One problem encountered with the making of snow roads is that the snow in the polar and subpolar regions is very dry, that is, the snow posseses little water in a fluid or irregularly crystallized state, which would aid in the compacting of snow into a uniform surface. This "dry" snow is often powdery in direct contrast to the "wet", well-packing snow so often used by children for making snow balls and snow men.
Because the dryness of the polar snow causes it to have poor compaction, conventional equipment and methods for the manufacture of snow roads usually involve partially melting the snow and ice which will, when frozen, form the road surface. This partial melting can occur in several ways. Heat can be directly applied to the snow or ice surface to melt it, thereby making the surface more compactable. Alternatively, the snow to be compacted can be lifted from the intended road surface, partly melted by a heater, and returned to the surface for compaction.
Each of these, however, is inefficient in its use of energy. The direct application of heat to the snow and ice often results in the unnecessary release of substantial amounts of heat to the surrounding air, rather than being absorbed by the ice and snow. Any irregularities in the density of the ice or snow can result in gross irregularities in the level of the road surface on compaction. Of course, the lifting of a significant quantity of snow into a vehicle for partial melting results in the wasted effort of lifting that portion of snow and ice which will remain frozen.
Prior to the present invention it has not been possible to construct a snow road with sufficient uniform density to assure safe travel and which could be safely used as a landing strip for aircraft.